Adapt feasibility-cli.js scoring for freeform idea text

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Context

#5136 (Idea feasibility & content-moderation pre-check) bundles an engineering task — adapting existing feasibility scoring for a new, freeform input shape — with a policy call (what counts as abusive/illegal intent). Splitting lets the engineering half be contributor-eligible; #5136 itself now covers the content-moderation policy call only.

Dependencies

Blocked on #4779 (Idea-intake bridge schema) being approved — it defines the input shape this scores.

Requirements

1. Check whether packages/gittensory-miner/lib/feasibility-cli.js's existing scoring approach can be adapted for freeform natural-language idea text (Rent-a-Loop's intake shape, per Idea-intake bridge schema #4779) before building a parallel mechanism from scratch.
2. Implement a pre-execution feasibility check, run post-schema-validation and pre-compute-allocation, that rejects or flags ideas that are well-formed but out-of-scope or impossible to evaluate objectively.
3. Document the adaptation: what was reused from feasibility-cli.js as-is, what needed changing for freeform text.
4. Out of scope: defining what counts as abusive/illegal intent — that remains Content-moderation policy for submitted ideas #5136's own scope.

Deliverables / Acceptance Criteria

• A feasibility check applied to a submitted idea, post-schema-validation and pre-compute-allocation
• A well-formed but out-of-scope/impossible idea is rejected or flagged before compute is allocated
• Written documentation of what was reused from feasibility-cli.js vs. newly built

Test Coverage Requirements

This PR must ship with full test coverage for every changed line and branch — the repo's Codecov patch gate requires 99%+ coverage. Cover at minimum: a feasible idea (passes), an out-of-scope idea (rejected/flagged), and a genuinely ambiguous idea (documented handling).

Expected Outcome

A customer can no longer pay for, or burn free-trial compute on, an idea that was never going to succeed — closing the engineering half of the pre-execution gap #5136 originally covered end to end.

Links & Resources

• packages/gittensory-miner/lib/feasibility-cli.js (the existing scoring approach to adapt)
• Idea-intake bridge schema #4779 (the idea-intake schema this scores)
• Content-moderation policy for submitted ideas #5136 (the issue this splits from — now covers the content-moderation policy call only)

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JSO-3885